The present invention relates to a lighting apparatus for raising natural lawn grass which is used for maintenance of natural lawn grass planted in the ground such as a soccer stadium, a rugby pitch, an athletic field, a tennis court, a baseball field, or a golf course.
Herein and in the appended claims, the upper side, lower side, left-hand side, and right-hand side in FIGS. 1 and 3 will be referred to as “upper,” “lower,” “left,” and “right,” respectively. The lower side in FIGS. 2 and 4 (the right side in FIGS. 5 to 7) will be referred to as “front,” and the side opposite thereto will be referred to as “rear.”
Conventionally, the maintenance of natural lawn grass planted in the ground of the above-described field or the like has been typically performed by naturally raising the natural lawn grass by means of sunlight during recovery periods. However, raising of natural lawn grass by means of sunlight has a problem of being time consuming. In addition, in the case where a structure such as stands or a roof is present, it is impossible to avoid formation of a region which is in the shade over a long period of time. Therefore, there has been a problem in that the growth of natural lawn grass is delayed in an area where the natural lawn grass receives little sunshine, and the growth of the natural lawn grass varies between an area where the natural lawn grass receives a lot of sunshine and an area where the natural lawn grass does not receive a lot of sunshine.
An apparatus which overcomes such a drawback has been proposed (see US2001/0035468 A1). In order to accelerate the growth of natural lawn grass of the above-described field or the like and suppress variation in growth thereof, the proposed apparatus emits or radiates artificial light onto the natural lawn grass when the natural lawn grass is to be recovered.
The apparatus disclosed in the US publication includes a horizontal frame having a rectangular shape as viewed from above; four support legs projecting downward from the four corners of the frame and supporting the frame; casters attached to the lower ends of the support legs and having wheels which rotate in the same direction and whose orientations are fixed; a plurality of stationary beams for lamp attachment which are fixedly provided on the frame; and a plurality of lamps attached to the stationary beams for lamp attachment. Artificial light is radiated onto natural lawn grass from the lamps attached to the stationary beams for lamp attachment. In the apparatus disclosed in the US publication, when the natural lawn grass is not required to be irradiated with artificial light, the apparatus is stored in a shed, and only when the natural lawn grass must be irradiated with artificial light, a required number of the apparatuses corresponding to the size of the ground are disposed above the natural lawn grass for use. Therefore, the apparatus is moved between the shed and a location on the natural lawn grass by making use of the casters at the lower ends of the support legs.
However, in the case where the apparatus disclosed in the US publication is used for raising the natural lawn grass of a large-scale ground such as the ground of a soccer stadium, the following problems arise. In order to decrease the number of the apparatuses, the size of each apparatus must be increased and the shed must have a large storage space. In addition, an operation of moving each apparatus is troublesome. When the size of each apparatus is reduced, a larger number of the apparatuses become necessary, and movement of the larger number of the apparatuses needs much labor and time.